Answer:
Prepositional phrase: Behind Elizabeth.
Use: Adverb
Step-by-step explanation:
A prepositional phrase is a group of words usually begins with a preposition and concludes with either a noun, pronoun, gerund, or clause as the object of preposition along with the modifier of the object. They may function either as an adverb or adjective that modifies or describes either the verb or the noun. In this given example, the prepositional phrase employed is "Behind Elizabeth" which is functioning as an adverb.